My vote goes to Google, to whom I am tightly married. It’s ecosystem and interconnectivity between apps as well as devices is unbeatable. It’s super reliant.
It’s the one entity that can wreck my online and offline presence. I mean, I use android and Google to login everywhere. If Mr. Google so decrees, my phone could wipe and google account be gone tomorrow. Same applies to Apple and Microsoft, but I don’t use their systems as much. The poison I picked is Google and I hate it.